The handedness of a particular door installation is determined by the direction in which the door pivots when moved from a closed position to an open position. If a door must be pivoted in a counterclockwise direction to open it, the door installation is considered to be left-handed. In a right-handed door installation, the door is pivoted in a clockwise direction to open it. Left-handed doors are hung from a jamb using a left-handed hinge, unless a non-handed hinge is employed. Similarly, either a right-handed hinge or a non-handed hinge may be used in right-handed door installations.
In FIG. 3 of my U.S. Pat. No. 3,903,567, there is illustrated a two knuckle hinge comprising a pair of adjacent hinge leaves on which short and long axially aligned hinge knuckles, respectively, are formed. A pintle, about which the long hinge knuckle pivots, is supported in the short hinge knuckle and extends into the long hinge knuckle. The pintle includes an external flange located in the end of the short hinge knuckle adjacent the long hinge knuckle for providing an anti-friction surface for a bushing and for preventing the pintle from being driven out of either hinge knuckle.
In mounting a door from a jamb, the leaf with the short hinge knuckle must be attached to the jamb so that the short hinge knuckle and the pintle will actually support the rest of the hinge assembly. Because the hinge has only a single vertical load or thrust bearing, i.e., the bushing which engages the flange on the pintle, if the leaf with the short hinge knuckle were attached to the door, rather than the jamb, with the long hinge knuckle positioned above the short hinge knuckle, the weight of the door would tend to separate the hinge knuckles, rendering the thrust bearing ineffective and possibly pulling the pintle out of the long hinge knuckle.
By applying the above-described principles for determining the handedness of a hinge, it can be determined that the two knuckle hinge illustrated in FIG. 3 of my U.S. Pat. No. 3,903,567 is left-handed, and, therefore, it cannot be used in right-handed door installations. Thus, handed two knuckle hinges, whether right-handed or left-handed, are restricted solely for use in similarly handed door installations.